VIBRATIONAL PREDISSOCIATION SPECTROSCOPY OF CS-5)((H2O)(1)

Infrared spectra of Cs+(H2O)(1-5) were obtained from vibrational predi ssociation of mass-selected cluster ions in a triple quadrupole mass s pectrometer using a pulsed-tunable infrared laser in the 2.6-3.0 mu m region. By comparison to size-selective infrared spectra of neutral wa ter clusters, the structure of hydrogen-bonded water clusters complexe d to the Cs+ can be observed for cluster ions with three or more water molecules. The onset of hydrogen bonding is also marked by the presen ce of structural isomers. There is also evidence for an unusual change in the vibrational transition moments for the symmetric and asymmetri c O-H stretch, for isolated (non-hydrogen-bonded) water molecules, whe re the symmetric stretch is substantially enhanced. (C) 1996 American Institute of Physics.